The preparation of polyether carbonate polyols by catalytic reaction of alkylene oxides (epoxides) and carbon dioxide in the presence of H-functional starter substances (“starters”) has been the subject of intensive study for more than 40 years (e.g. Inoue et al., Copolymerization of Carbon Dioxide and Epoxide with Organometallic Compounds, Die Makromolekulare Chemie 130, 210-220, 1969). This reaction is shown in schematic form in scheme (I), where R is an organic radical such as alkyl, alkylaryl or aryl which may in each case also contain heteroatoms, for example O, S, Si, etc., and where e, f, g and h are each integers, and where the product shown here in scheme (I) for the polyether carbonate polyol should be understood as meaning merely that blocks having the structure shown may in principle be retained in the polyether carbonate polyol obtained but the sequence, number and length of the blocks and the OH functionality of the starter may vary and is not restricted to the polyether carbonate polyol shown in scheme (I). This reaction (see scheme (I)) is highly advantageous from an environmental standpoint since this reaction comprises converting a greenhouse gas such as CO2 into a polymer. A further product formed, actually a by-product, is the cyclic carbonate shown in scheme (I) (for example propylene carbonate when R═CH3, also referred to hereinafter as cPC, or ethylene carbonate when R═H, also referred to hereinafter as cEC),

EP-A 0 222 453 discloses a process for preparing polycarbonates from alkylene oxides and carbon dioxide using a catalyst system composed of DMC catalyst and a cocatalyst such as zinc sulfate. WO-A 2003/029325 discloses a process for preparing high molecular weight aliphatic polyether carbonate polyols (weight-average molecular weight greater than 30 000 g/mol), in which a catalyst from the group consisting of zinc carboxylate and multimetal cyanide compound is used. WO-A 2008/092767 discloses a process for preparing polyether carbonate polyols, characterized in that one or more H-functional starter substances are initially charged in the reactor and in that one or more H-functional starter substances are metered continuously into the reactor during the reaction.
U.S. Pat. No. 3,829,505 and DE 1 595 759 describe the possibility of reacting OH-functional starter compounds in excess with aromatic polyisocyanates, in order to arrive in this way at polyurethane polyols containing OH groups and having at least 2 urethane groups, which can be used as starter oligomers for the DMC catalysis.
U.S. Pat. No. 3,654,224 describes the possibility of using amides, especially aromatic amides, for example benzamide, as starter compound for the DMC catalysis.